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Very dry air this week

May 18, 2012

Very dry air this week

Following a wet first ten days of the month, May turned quite dry
this week, with low dewpoints and high evaporation rates (0.25 to 0.35
inches on May 14). Montevideo (Chippewa County) reported some
record-setting low daily humidity readings over May 12-16. Afternoon
air temperature and relative humidity are noted for each day:May 12 70 degrees F with RH of 7%May 13 75 degrees F with RH of 11%May 14 88 degrees F with RH of 4%May 15 72 degrees F with RH of 12%May 16 73 degrees F with RH of 14%

These
humidity readings at Montevideo were the equivalent of those at Tucson,
Arizona this week. Many Minnesota citizens were using moisturizing
creams and chapstick.

Cold morning on May 16th

After a very warm Monday this week (afternoon temperatures ranged from
86 F to 90 F in western Minnesota), Minnesota reported the coldest
temperature in the 48 contiguous states on Wednesday morning (May 16)
with a reading of 24 degrees F at Embarrass, the first time this month
that the state has reported the coldest reading. Many observers reported
overnight lows in the 20s F on May 16th including 28 degrees F at
Warroad, Cook, Hibbing, Bigfork, Ely, Grand Marais, and Kabetogama, 27
degrees F at Orr,Silver Bay, and Crane Lake, and 26 degrees F at
International Falls. These overnight readings represent new record lows
for May 16th at Kabetogama and Orr, and ties the record low for Crane
Lake.

NOAA CPC Climate Outlook

On Thursday, May 17, NOAA-Climate
Prediction Center release a new climate outlook for June through August.
The outlook suggests equal chances for warmer or colder than normal
temperature conditions over the summer in Minnesota. It also suggests
equal chances for a wetter or drier than normal summer.

Weekly Weather Potpourri

The May 16th report from the
Amundsen-Scott Weather Station at the South Pole (Antarctica) was -77
degrees F with an east wind of 10-15 mph and a windchill of -114 degrees
F.

The NOAA National Hurricane Center in Miami, FL was issuing
advisories this week on the first Tropical Storm of the 2012 season in
the Eastern Pacific. Tropical Storm Aletta was generating winds of 40
mph and sea waves of 12 feet as it moved westward well off the coast of
Mexico. It is expected to dissipate over the next several days.

Scientists
from the University of Utah and Harvard University have developed a new
way to estimate carbon dioxide emissions based on measured pattern
detection in the atmosphere. This technique may be further refined to
be used as a compliance validation measurement system should an
international treaty ever be invoked that forces reduction in carbon
dioxide emissions over specified periods of time. You can read more
about their work here.

MPR listener question

How much does a large thunderstorm cloud weigh? It must contain a lot of water.

Answer:
Thomas Schlatter, a NOAA scientist and contributor to Weatherwise
magazine addressed this question in a past issue. Of course the answer
is highly dependent on cloud volume. But consider a cumulus cloud with a
volume of one cubic mile (1 mile wide, 1 mile long, and 1 mile deep)
and a water content of 1 gram/cubic meter. This would calculate to a
weight of about 9 million pounds (nearly 1.1 million gallons). That's
quite a load to remain suspended in the atmosphere, but of course it
does, primarily because of the droplet size and the updraft winds that
hold these water droplets aloft until they reach a critical mass.

Twin Cities Almanac for May 18th

The average MSP high temperature for this date is 69 degrees F (plus or
minus 11 degrees F standard deviation), while the average low is 49
degrees F (plus or minus 7 degrees F standard deviation).

Average dew point for May 18th is 46 degrees F, with a maximum of 72 degrees F in 1998 and a minimum of 19 degrees F in 2002.

All-time state records for May 18th

The state record high temperature for this date is 101 degrees F at
Fairmont (Martin County) and Pipestone (Pipestone County) in 1934; the
state record low temperature for this date is 16 degrees F at the Duluth
Experimental Farm (St Louis County) in 1924. State record
precipitation for this date is 5.01 inches at Lanesboro (Fillmore
County) in 2000; and state record snowfall for this date is 3.0 inches
at Minneapolis (Hennepin County) in 1915.

Past Weather Features:

May
of 1892 was one of the wettest in Twin Cities history. It rained
everyday from 13th to the 21st (totaling nearly 4 inches). Farmers were
late in planting crops that year because it rained on 18 days during
the month. Many observers reported 6-8 inches of rainfall for the
month, and Northfield reported nearly 10 inches.

May 18, 1915
brought cold and snow to many places in the state. Park Rapids and
Caledonia observers reported 1 inch of snowfall, while Taylors Falls
reported 1.5 inches. In Minneapolis an observer recorded 3 inches of
snowfall, still a record for the date.

About 8:30 pm on May 18,
1918 an F-2 tornado (winds 113-157 mph) moved 8 miles across the rural
landscape of Big Stone County in western Minnesota. It damaged
buildings on 30 farms, but caused no injuries.

May 17-18, 1968
brought snow to many northern Minnesota communities, in one of the
latest spring snow storms on record. Duluth reported 3.6 inches, Grand
Rapids 3.0 inches, and Mahnomen 2.0 inches. As far west as Milan
(Chippewa County) reported 0.5 inches. Temperatures warmed into the 50s
and 60s F the next day so the snow was very short-lived.

May 18,
2000 brought heavy thunderstorms and flash flooding to many southern
Minnesota communities. Jackson, St Peter, Wells, Grand Meadow, Hokah,
Preston, Rushford, and Rochester measured over 4 inches of rain. Huge
drifts of hail stones piled up near Mankato and there was reported crop
damage in many areas. Many roads were closed, one due to a mud slide in
Winona County.

Most recently on May 18, 2002 a hard freeze
visited many northern Minnesota communities. Many areas saw morning
lows in the 20s F, while Tower reported just 18 degrees F and Embarrass
was the coldest with 17 degrees F.

Outlook

Generally a warm Saturday with chances for showers and thunderstorms.
Cooling down on Sunday and Monday with a continued chance for showers.
Drier on Tuesday. Warmer with another chance for showers by Thursday
next week.